Spark-plug



A. K. ROBERTS.

SPARK PLUG. APPLICATION FILED APR'.15, 1919,-

Patnted May M), 1921 u (au) arten sraries PATENT erica,

.ARTHUR K. ROBERTS, OF QUNCY, MASSACHUSETTS.

SPARK-PLUG.

Specification of Letters Patent.

Application led April 15, 1919. Serial No. 290,127.

To all whom t may concern.'

Belit known that I, ARTHUR K. ROBERTS, a citizen of the United States, residing at Quincy, in the county of Norfolk and State of,y Massachusetts, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

This invention relates to spark plugs, such as are used in connection with internal combustion engines, and an object of the in-l i movement thereof, with respect to the spark plug, under vibratory movement of the plug which might be occasioned by the operation of the engine or motor in connection with which the spark plug is used.

A still further object of the invention is to provide a spark plug including a pair of Hat relatively large sparking points, which are spaced relatively close to each other for creating a broad spark at all times.

Other objects of the invention will appear in the following detailed description taken in connection with the accompanying drawings, forming a part of this specification, and in which drawings:

Figure l is a side elevation of the improved spark plug.

FigLQ is a longitudinal section thi-"ough the plug, and

` Flg. 3 is a horizontal section taken on the line 3 3 of Fig. 2. j

Referring more particularly to the drawings, 1 indicates the metal shellof the spark plug, which is threaded, as shown at 2, for connection with the engine or motor cylinders. The shell 1 carries the usual insulating core 3 of porcelain or analogous insulating material through the center of which the centra-l electrode 4f of the spark plug'extends. The upper end of the central electrode 4 may be formed in any approved manner to facilitate the connection of a battery connector and conductor thereto. The lower endr of the central electrode 4 has a disk 5 formed thereupon, forming the sparking terminal ofthe electrode which coacts with the electrode 6 informing the spark.

\. The electrode 6 is substantially cupshaped and is provided with an internal threaded portion 7 adapted for threadable connection with the lower end of the shell l, to permit of adjustment of the cup-like electrode 6 with respect to the shell and also with respect to the disk terminal of the central electrode 4.. The electrode G is provided with a plurality of circumferentially spacedopenings 8, therein, near its lower end as clearly shown in the drawings, forming a-plurality of ribs 9 which are spaced from the disk terminal 5. The openings 8 permit the combustible gas to enter the cuplike electrode 6, about the terminal 5 for igniting it upon the creating of a spark between the terminal 5 of the electrode 4 and the bottom l() of the cup-like electrode 6.

Patented lllay lll, 1921.

A plurality of set-screws l1 extend diametrically through the cup-like electrode 6 near its upper edge and the inner ends of these set screws are adapted to bite into the shell l, for securely connecting the electrode 6 to the shell and prevent adjustment or movement of the electrode (3 with respect to the shell, under vibration of the spark plug, thereby securely locking thc sparking point or portion of the electrodes 5 and (3 in adjusted positions.

By providing the disk 5 upon the terminal of the electrode 4, and placing it relatively close to the fiat upper surface of the electrode 6, a broad or fat spark will be created at all times, during the operation of the spark plug, owing to the fact that a spark occurring between two flat surfaces in so smallra space will necessarily be relatively broad, thereby insuring the proper ignition of fuel "about the electrodes and materially decreasing liability of misiring ofthe spark plugl and fuel.`

Changes in details may be made without departing from the spirit'of this invention, but;

I claim:

l; ln a spark plug, the combination, of a shell, a central electrode extending axially through said shell, a second electrode adjustably carried bythe inner end of said shell for adjusted movement toward or from the terminal of said central electrode, a setv screw extending through said adjustable electrode and adapted for biting engagenient` with said easingto lock said adjustable electrede against movement.

2. ln a spark plug, the combination, of a casing, a. Central electrode extendingaxiallyY through said casing, a disk lerniinal formed.-

upon the inner end of said central electrode, an adjustable electrode carried by 'die inner end ofisaid Casing and adapted for adjusted movement toward or from said disk ternir nali and a set screw extending` through said adjustable electrode 4and adapted for biting` engagement with said shell. to look he adjusted electrode against inoveinei'i.

3. n a spark plug, the combination, of a shell, a Central electrode'extending axially through saidshell, a disk terminal formed upon the lower end of said electrode, a ouplike elecrode adjustahly connected to the inner end of said shell, and adapt-ed for adjustedy movement with respect to said disk terminal, said cup-like eleetrode provided with a pluralijv of cireuniiierentially spaced openings formed in its sides, near its lower end, and a plurality of set screws extending througfgh the sides of said cup-like electrode and adapted to bite into said. shell co lock 'the adjustable eleerode in adjusted position.

ARTHUR K. ROBERTS. 

